Diamond Junction Produces UV Light
Brian Dance, Contributing Editor -- Semiconductor International, 10/1/2001
Diamond has an extremely wide energy bandgap of 5.46 eV, so a diamond LED or even a laser should produce UV light at room temperature. However, diamond is normally a p-type material, and it has proved very difficult to make n-type diamond.
Satoshi Koizumi of the Japanese National Institute for Materials Science (Tsukuba, Japan) has grown both n- and p-type layers on a thin film of diamond to produce a p-n junction. Electron mobility in the p-type material is about 300 cm2/Vsec, some 5× greater than the electron mobility in the n-type material.
When a forward voltage of 20 V was applied, UV radiation was emitted from the junction with a wavelength of about 235 nm. It was accompanied by longer-wavelength visible light. It may be possible to prevent the latter by improving the quality of the boron-doped p-type region.
